Electromechanic driving mechanism for the hands of a timepiece

ABSTRACT

A driving mechanism for a timepiece comprises a shaft which rotatably mounts a stepping anchor and a coil. The coil is disposed between a plurality of permanent magnets. Suitable electrical connections are provided between the coil and an impulse generator. The coil may be asymmetrically arranged on the shaft to compensate for unbalances in the mechanism. Alternately, a bushing or disk may be mounted on the shaft to compensate for unbalances.

United'States Patent Ganter et al. Jan. 8, 1974 [54] ELECTROMECHANIC DRIVING 3,472,020 10/1969 Jackle 523/28 R MECHANISM FOR THE HAND OF A 3,553,957 l/l97l Dome et a1. 58/23 A TIMEPIECE 3,597,914 8/1971 Meitinger 58/107 3,604,201 9/1971 Dome 58/116 [75] Inventors: Wolfgang Gamer, 3,665,697 5/1972 Dome 58/28 D Schramberg-Sulgen; Horst Dinger, Tennenbronn, both of Germany [73] Assigneez Firma Gebruder Junghans Prirnary Examiner-Richard B. Wilkinson Schramberg Germany Assistant Exammer-U. Weldon Attorney-James E. Cockfield [22] Filed: July 27, 1972 [21] Appl. No.: 275,872

301 Foreign Application Priority Data [57] ABSTRACT July 29, I971 Germany P 07 12 931.8 I I July 29, 197] Germany P 07 I2 93m A driving mechanlsm for a tlmeplece compflses a shaft which rotatably mounts a stepping anchor and a 52 U5. Cl. 5808 B, 58/23 D coil- The coil is disposed between a plurality of perma- 51 Int. Cl. G04b 17/00 Hem magnets Suitable electrical connections are p 53 Fidd f Search 5 23 R 23 A 23 AC vided between the coil and an impulse generator. The 53/23 D 23 v 23 R, 2 B, 2 D 1 R, 1 coil may be asymmetrically arranged on the shaft to M 107; 310/3 compensate for unbalances in the mechanism. Alternately, a bushing or disk may be mounted on the shaft [56] References Cited to compensate for unbalances.

UNITED STATES PATENTS 3,095,690 7/1963 Epperlein 58/28 B 11 Claims, 8 Drawing Figures PATENTEU 8*974 3.783.600

SHEET 3 [If 4 PAIENTEBJAN 8 1974 SHEET Q (If 4 ELECTROMECHANIC DRIVING MECHANISM FOR THE HANDS OF A TIMEPIECE BACKGROUND OF THE INVENTION The invention relates to an electromechanical driving mechanism for the hands of a timepiece, especially a quartz wristwatch, including a coil and a stepping anchor, as well as a permanent magnet system acting on the coil.

Such a driving arrangement is known for a quartz wristwatch, see German published application no. 1,809,223. In this case, a fixed coil and a rotatable permanent magnet arrangement are provided. This known driving arrangement has relatively large dimensions and it has a relatively large flywheel effect. Furthermore, it is difficult to achieve a precise balancing of the movable part. A relatively small unbalance, however, produces a relatively large torque on the movable part under certain circumstances, namely, whenever the unbalance has a certain position relative to a thrust acting on the watch. As a result of such large torque, an imperfect shifting is brought about. Such unbalances are a result, for example, of the finishing tolerances as well as a result of different accumulations of adhesive substances, lacquer or soldering tin. The elimination of these unbalances often is not simple, especially when the rotatable part of the stepping arrangement carries the permanent magnet system. 1

The following requirements are made of a driving arrangement of the above mentioned type:

1. as good a degree of effectiveness as possible is required;

2. the device is to have, as much as possible, a flat type of construction;

3. the driving arrangement is to be easily producible and exchangeable;

4. the supply of current to the coil is to be simple and safe;

5. the swinging movement of the rotatable part of the driving arrangement is to be limited in a simple manner.

These requirements are not fulfilled by the known driving arrangement.

OBJECTS AND SUMMARY OF THE INVENTION such a driving arrangement which has relatively small.

dimensions and a minimized flywheel effect.

It is a further object of the invention to provide such a driving arrangement which facilitates the elimination of unbalances which may exist in the timepiece.

According to a preferred embodiment of the invention these objects are achieved by mounting the coil for rotation together with the stepping anchor. The coil is wound in the shape of a rectangle and is disposed on a shaft running at right angles to the winding plane of the coil. The shaft is enclosed so that the permanent magnet system is provided with four air gaps through which the magnetic flow permeates, whereby each air gap contains a conductor bundle of the coil. A significant aspect of the invention concerns an electro-mechanical driving arrangement of relatively low height in construction, and being generally of a simple structure. At the same time, its effectiveness is of a high degree.

For practical purposes a plate provided with electrically conductive strips is disposed coaxially to the coil, the electrically conductive strips of which are connected with the ends of the coils. This plate is developed preferably as a support for the coil. At the same time, the electrically conductive strip connected with one end of the coil is connected with an outlet of an impulse generator by way of the shaft bearing the coil and a spiral spring attached to the shaft. The electrically conductive strip connected with the second end of the coil leads via a spring, bent in meander shape, to a fixed connecting plate insulated against mass, which plate is connected with the second outlet of the impulse generator.

Effectively, the permanent magnet system is composed of four cubic two-pole permanent magnets that are attached on a plate of the watch mechanism and on a special bridge, and which form four magnetic air gaps for the conductor bundles of the coil. The four cubic permanent magnets are covered, on their sides facing away from the air gaps, with magnetically conductive return elements. At the same time, the bridge itself is developed as a magnetic return.

In order to compensate for the unbalance brought about by the stepping anchor, a bushing causing a compensatory unbalance and supporting the coil is, for practical purposes, disposed on the shaft. This bushing has two flattenings running parallel to one another and parallel to the shaft, whereby the coil is placed on that part of the bushing provided with said flattenings. Furthermore, the distances of the flattenings from the shaft are selected differently in such a way that the unbalance caused by the asymmetrical arrangement of the coil relative to the shaft compensates for the unbalance brought about by the stepping anchor.

Furthermore, an additional mass is disposed on the bushing to make possible a precise adjustment of the unbalance. Thus, a disk provided with a recess on one side is disposed on the bushing, which disk compensates for the unbalance brought about by the stepping anchor. The disk may be provided with a recess that is shaped like a section of a circular ring.

As a result of the development provided according to the invention, a rough balancing of the unbalance brought about by the stepping anchor is achieved and, furthermore, it is possible to achieve an additional balancing in a simple manner that is required for compensation of the finishing tolerances. THE DRAWINGS The invention is explained in more detail in the following pages on the basis of the drawing and by way of embodiments presented as examples. In the drawing:

FIG. 1 shows a perspective view of an electromechanical driving arrangement according to the invention;

FIG. 2 shows a perspective view of the movable part of the driving arrangement according to FIG. 1, including a coil and stepping anchor;

FIG. 3 shows a view of a plate carrying the coil, viewed in the direction of arrow A in FIG. 2;

FIG. 4 is a top view of the driving arrangement according to FIG. 1, whereby a part of the permanent magnet system is left out, and a view of the step wheel being driven by the driving arrangement;

FIG. 5 is a side view of a modified embodiment of the device according to the'invention and given by way of example, whereby individual elements are cut away;

FIG. 6 is a cut following line VIVI in FIG. 5;

FIG. 7 is a side view of an additional embodiment given by way of example, in which the parts have been cut away; and

FIG. 8 is a view of the embodiment given by way of example according to FIG. 7 viewed in the direction of arrow B in FIG. 7.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION In FIG. 1 the base plate is designated by 10 and the special bridge by 11. These parts are supports of four two-pole permanent magnets 12 of a type known per se. The permanent magnet system formed in this way has a small magnetic leakage. Preferably, cubic permanent magnets are used, each one having two opposite poles and which are attached by glueing or cementing. Bridge 11 can serve as a magnetic return element, which in this case is made of a raw material of high permeability. The magnetic return connection for the permanent magnets 12, which are attached to base plate 10, is accomplished preferably by special plates 13 made of a raw material having good magnetic conductivity.

In the air gaps 14, 15, 16 and 17 of the magnetic system there are disposed four conductor sections, or bundles, 18a, 18b, 18c and 18d of a rectangularly wound coil 18 whenever this coil is in its rest position.

As is clear from FIG. 2, coil 18 is fixed axially between a conductor plate 19 and a stepping anchor 20 of the pallets. The radial fixing is accomplished by means of a shaft 21 bearing coil 18 and anchor 20. Preferably, the plate 19 functions as a support to carry the coil 18.

As shown in FIG. 3, the conductor plate 19 has two conductor paths 19a and 19b on the side facing away from the coil. The beginning and end of the coil are guided through bores 19a and 19b and are connected galvanically with the corresponding conductor paths.

The conductor path 19a extends around shaft 21 with the positive connection for example for the purpose of supplying current, so that in this case galvanic connections likewise are possible between shaft 21 and conductor path 19a, preferably by means of soldering. These connections are designated by 22. A spring 23 conducts current between the shaft 21 and the bridge 11 (FIG. 1). The current supply thus leads from shaft 21 via spiral 23, bridge 11 to the mass of the watch mechanism.

The other current supply, for example to the negative connection, is accomplished as follows: Preferably a meander shaped spring 26 is connected galvanically at points 27 and 28 (FIG. 1) with conductor part 19b and a small connecting plate insulated by a plate 24. The small connecting plate 25 has a bore 250 which permits a releasable connection to the electronic circuit structure.

In order to produce the current impulses feeding the coil 18, an impulse generator 18' (shown schematically in FIG. 1) is used, the frequency of which is stabilized for example by means of a quartz crystal and the output frequency of which is stepped down by means of several voltage divider stages to a frequency suitable for the drive, for example one Hz. The conductor part 19a,

shaft 21, spiral 23, and bridge 11 define an electrical conductor between one end of the coil and an outlet of the generator. The conductor part 19b, spring 26, and plate 25 define an electrical conductor between the other coil end with the other generator outlet.

FIG. 4 shows an embodiment by way of example, in which the driving arrangement steps up a step wheel 29 for the seconds. The position of coil 18 and anchor 20 as drawn is the rest position.

In order to prevent return of step wheel 29 during the stepping process, a blocking wheel 30, for example, can be used with a blocking spring 31.

In FIGS. 5 and 6 an example of the holding construction and fixation of the coil 18 used advantageously is shown. A bushing 42, with which coil 18 is connected galvanically by means of a conductor plate 43, serves for this purpose and said coil 'fits against a stepping anchor designated by the numeral 44. The conductor plate 43 preferably is a plastic plate onto which are applied electrically conductive paths in a known manner. The plate and bushing are attached to the anchor shaft 45.

Bushing 42 has flat surfaces 42a, 42b which are at unequal distances from the rotating axle 44a. As a result of that, coil 18, and thus its weight, is shifted relative to the rotational axle 44a of anchor 44. The measure by which coil 18 is shifted is designated by the numeral a (FIG. 6). This measure is selected such that the weight of arms 44b, 44c, including pallets 44b and 440, is compensated. The attachment of the coil 18 to surfaces 42a, 42b of bushing 42 and on the conductor plate 43 is accomplished by any suitable means, preferably by bonding or glueing together with lacquer.

In the embodiment given as an example according to FIGS. 5 and 6, an annular attachment 420 is suitably provided on bushing 42 and effectively constitutes an extension thereof. This attachment serves for facilitating the dynamic precision balancing, by machine, of a perhaps still existing residual unbalance as well as an unbalance that may have resulted during assembly of the driving arrangement resulting from finishing tolerances, as well as due to accumulations of adhesives, lacquer and soldering tin on conductor plate 43. The removal of material by means of a balancing machine is accomplished for example by means of drillings 420'.

As shown in FIGS. 7 and 8, according to a further embodiment given by way of example and in such cases where for constructional reasons sufficient shifting of the coil is impossible, the annular extension 42c of bushing 42, utilized in conjunction with the FIGS. 5 and 6 embodiment, can be replaced for the purpose of balancing by machine, by a disk 50 disposed separately on the anchor shaft. This shaft, as shown in FIG. 8, has a massive sector 50a as additional compensation for the mass of the anchor arms 44b and 440. Again, removal of material that might have to be accomplished by the balancing machine is designated by the numeral 50b. A recess 50c, shaped in the form of a circular ring section, may be formed in the disk 50. In cases where additional balancing elements are utilized, such as a disk 50, the

coil may be arranged symmetrically with respect to the anchor shaft.

MAJOR ADVANTAGES AND SCOPE OF THE INVENTION The invention provides an effective driving mechanism for a timepiece which may be constructed with relatively small dimensions. The utilization of a rotatable coil affords a minimized flywheel effect. By arranging the coil asymmetrically with respect to the anchor shaft, unbalances in the mechanism may be conveniently compensated for. The employment of a bushing 42 or a disk 50 provides a further means of compensating for unbalances. The supply of current to the coil is accomplished through a system which is simplified and safe.

The invention is not limited to the embodiments shown by way of example. Rather the invention also comprises modified embodiments by way of example insofar as the modifications are within the scope of the invention.

What is claimed is:

1. In a watch having an electromagnetic driving mechanism which includes a coil, permanent magnet means acting upon the coil, and stepping anchor means, the improvement comprising:

said stepping anchor being mounted for rotation on a shaft;

said permanent magnet means comprising four twopole permanent magnets defining four air gaps permeated by magnetic flux;

said coil being wound in the shape of a rectangle which encloses and extends at a right angle to said shaft;

said coil being arranged such that four rectilinear conductor sections of the coil are operably contained by the air gaps;

said coil being mounted for rotation with said stepping anchor on said shaft.

2. Apparatus according to claim 1 wherein:

a conductor plate is disposed coaxially with respect to said coil;

said conductor plate including a plurality of electrically conductive strips connected to respective ends of the coil.

3. Apparatus according to claim 2 wherein said conductor plate is arranged to carry said coil.

4. Apparatus according to claim 2 wherein said driving mechanism further includes:

an impluse generator including a quartz crystal means;

a spiral spring operably connected between said shaft and said generator; one of said conductive strips, said shaft, and said spiral spring being arranged to define an electrical conductor between one end of said coil and said generator;

a fixed, insulated connecting plate being operably connected to said generator;

a meandenshaped bent spring being operably connected between said connecting plate and the other of said conductive strips; said other conductive strip, said bent spring and said connecting plate being arranged to define an electrical conductor between the other end of said coil and said generator.

5. Apparatus according to claim 1 wherein said driving mechanism further includes:

a base plate;

bridge means;

said permanent magnets being connected to said plate and said bridge means;

said permanent magnets being arranged to define the air gaps containing said conductor sections of said coil;

said magnets having magnetic return means disposed on sides thereof facing away from the air gaps. 6. Apparatus according to claim 1 wherein said driving mechanism further includes:

bushing means, mounted on said shaft and operably engaging said coil, for producing a compensatory unbalance tending to compensate for an unbalance caused by movement of said stepping anchor means. 7. Apparatus according to claim 6 wherein: said bushing means includes a pair of flat surfaces extending parallel to each other and to said shaft;

said coil being arranged to engage said flat surfaces; said surfaces being unequally spaced from said shaft such that said coil is positioned asymmetrically with respect to said shaft;

said asymmetrically arranged coil, upon rotation, de-

fining means tending to substantially equalize the unbalance caused by said stepping anchor means.

8. Apparatus according to claim 7 wherein said driving mechanism further includes:

an attachment disposed on said bushing for effecting a precise adjustment of the unbalance.

9. Apparatus according to claim 6 wherein:

said coil being symmetrically arranged with respect to said shaft;

a disc being mounted for rotation on said shaft;

one side of said bushing being recessed to compensate for an unbalance caused by the stepping anchor means.

10. Apparatus according to claim 9 wherein:

said disk is provided with a recess having the shape of a circular ring section. 11. In a watch having an electromagnetic driving mechanism which includes a coil, permanent magnet means acting upon the coil, and stepping anchor means, the improvement comprising:

said stepping anchor being mounted for rotation on a shaft;

said permanent magnet means comprising four twopole permanent magnets defining four air gaps permeated by magnetic flux;

said coil being wound in the shape of a rectangle which extends at a right angle to said shaft;

said rectangular coil including integral pairs of long and short sides with said shaft being centrally located therewithin;

said coil being arranged such that four generally diagonally opposed, rectilinear conductor sections of the long sides of the coil are operably contained by the air gaps;

said coil being mounted for rotation with said stepping anchor on said shaft. 

1. In a watch having an electromagnetic driving mechanism which includes a coil, permanent magnet means acting upon the coil, and stepping anchor means, the improvement comprising: said stepping anchor being mounted for rotation on a shaft; said permanent magnet means comprising four two-pole permanent magnets defining four air gaps permeated by magnetic flux; said coil being wound in the shape of a rectangle which encloses and extends at a right angle to said shaft; said coil being arranged such that four rectilinear conductor sections of the coil are operably contained by the air gaps; said coil being mounted for rotation with said stepping anchor on said shaft.
 2. Apparatus according to claim 1 whErein: a conductor plate is disposed coaxially with respect to said coil; said conductor plate including a plurality of electrically conductive strips connected to respective ends of the coil.
 3. Apparatus according to claim 2 wherein said conductor plate is arranged to carry said coil.
 4. Apparatus according to claim 2 wherein said driving mechanism further includes: an impluse generator including a quartz crystal means; a spiral spring operably connected between said shaft and said generator; one of said conductive strips, said shaft, and said spiral spring being arranged to define an electrical conductor between one end of said coil and said generator; a fixed, insulated connecting plate being operably connected to said generator; a meander-shaped bent spring being operably connected between said connecting plate and the other of said conductive strips; said other conductive strip, said bent spring and said connecting plate being arranged to define an electrical conductor between the other end of said coil and said generator.
 5. Apparatus according to claim 1 wherein said driving mechanism further includes: a base plate; bridge means; said permanent magnets being connected to said plate and said bridge means; said permanent magnets being arranged to define the air gaps containing said conductor sections of said coil; said magnets having magnetic return means disposed on sides thereof facing away from the air gaps.
 6. Apparatus according to claim 1 wherein said driving mechanism further includes: bushing means, mounted on said shaft and operably engaging said coil, for producing a compensatory unbalance tending to compensate for an unbalance caused by movement of said stepping anchor means.
 7. Apparatus according to claim 6 wherein: said bushing means includes a pair of flat surfaces extending parallel to each other and to said shaft; said coil being arranged to engage said flat surfaces; said surfaces being unequally spaced from said shaft such that said coil is positioned asymmetrically with respect to said shaft; said asymmetrically arranged coil, upon rotation, defining means tending to substantially equalize the unbalance caused by said stepping anchor means.
 8. Apparatus according to claim 7 wherein said driving mechanism further includes: an attachment disposed on said bushing for effecting a precise adjustment of the unbalance.
 9. Apparatus according to claim 6 wherein: said coil being symmetrically arranged with respect to said shaft; a disc being mounted for rotation on said shaft; one side of said bushing being recessed to compensate for an unbalance caused by the stepping anchor means.
 10. Apparatus according to claim 9 wherein: said disk is provided with a recess having the shape of a circular ring section.
 11. In a watch having an electromagnetic driving mechanism which includes a coil, permanent magnet means acting upon the coil, and stepping anchor means, the improvement comprising: said stepping anchor being mounted for rotation on a shaft; said permanent magnet means comprising four two-pole permanent magnets defining four air gaps permeated by magnetic flux; said coil being wound in the shape of a rectangle which extends at a right angle to said shaft; said rectangular coil including integral pairs of long and short sides with said shaft being centrally located therewithin; said coil being arranged such that four generally diagonally opposed, rectilinear conductor sections of the long sides of the coil are operably contained by the air gaps; said coil being mounted for rotation with said stepping anchor on said shaft. 